SU99631A1 - A method of making masked color separations of negatives for reproducing color originals. - Google Patents

Description

In the process of reproducing color originals, three or more color separations of negatives are produced, taken from the original through various filters. Printed forms or matrices are then made from these negatives. Since the colors of the original and printing inks, as a rule, do not have matching absorption curves, additional correction of the color separations of negatives by retouching or using masks is required. With this method, a simultaneous or sequential printing is carried out from the color-separated images of the object taken in different regions of the spectrum. used as a combination of negative images taken in the same spectral region, with positives, taken in another spectral region, and a combination of negatives with negatives or positives with positives, taken in different spectral regions.

In all these cases, precise alignment of several color separation images is required.

The proposed method allows the combination of a masked image and a mask by

using bilayer or multilayer films with separate layers sensitized to different parts of the spectrum, which makes it possible to obtain a perfect match of the images obtained in different layers.

Separate layers of the emulsion may contain dyes that bleach at the sites of silver, or color components that fade at bleachers of metallic silver.

It is also possible to use emulsions that appear directly as positive.

Example 1. To obtain a yellow negative, a film with two layers is used, of which the upper is sensitized to blue and the lower is panchromatic. The upper layer is dyed with a yellow dye to trap blue rays. A yellow filter layer can also be used.

The lower layer contains a bleaching yellow dye in an amount of about 18 grams per kg of emulsion.

Shooting is done without a filter. Pierced silver bottom

the layer is bleached in the following solution; thiourea 60 g, hydroquinone 30 g, sulfuric acid 20 ml and water to 1 l.

In the places where silver is located, in the lower layer, the yellow dye is discolored. The silver image of the upper layer is retained, since the bleaching with thiourea occurs only in the presence of a yellow dye. The remaining positive yellow mask together with the top layer will give a normal gradation of the image through the blue filter.

Example 2 A bilayer film was used to make two purple negatives. The top layer consists of a directly positively-projected emulsion or a conventional emulsion, cut with a supranol-diamond paint, which is destroyed by bleaching silver in an acidic medium. The top layer is sensitive to blue and red rays, the bottom to green. Blue rays are trapped by a yellow filter. After bleaching, a positive image remains.

Example 3. A film for making a yellow negative consists of an upper layer sensitive to blue lisch, containing a pigment for a dye that absorbs blue, and a lower layer, panchromatic, containing a short yellow component that gives a chromogenic purple or blue dye.

After the occurrence, a yellow negative is obtained in the upper layer, and in the lower layer a positive yellow and a purple or blue negative.

Magenta and blue colors give an additional absorption during printing, which masks the masking effect, why this dye is destroyed by acid. The original yellow component is preserved. The dye of the upper part should be also acid-resistant.

Subject invention

Claims (3)

1. A method of making masked color-separated negatives for reproducing color originals, characterized in that, in order to produce a combined positive mask and color-separated negative, each color-separated negative is photographed on a two-layer or multilayer film, the layers of which have different sensitization and during photochemical processing, monochrome negative and positive images are formed. 2. A method according to claim I, characterized in that the positive mask layers contain dyes that are discolored at the bleaching points of metallic silver. 3. The method according to claim 1, characterized by HJ, and also with the fact that positive layers of directly developed emulsions are applied to the positive layers, which make it possible to directly obtain a positive image after exposure and appearance.